Laser processing is a method of performing surface modification such as welding, cutting, or laser peening or tempering (or quenching) of a region to be processed by directing a laser beam emitted from a laser oscillator onto the surface of the region to be processed, through an optical system comprising for example a lens or mirror provided in a laser irradiation head. The absorption rate of the laser beam varies depending on the material of the region to be processed and the type of laser oscillator employed, and various kinds of processing can be performed, depending on differences in laser output etc. For example, for laser welding or cutting, a YAG laser, CO2 laser or fiber laser or the like of high output in the several-kW class may be employed, and the quality of the laser-processed region may be varied by employing different laser waveforms, as a continuous wave or pulse.
In the case of laser welding, clad welding is performed using filler metal (or welding material). For example, in an atomic power plant, when repairing locations where stress corrosion cracking has occurred or locations where such cracking may occur, clad welding is performed using metal filler of superior stress corrosion cracking resistance. In this way, occurrence of stress corrosion cracking in locations where weld repair has been performed can be prevented. Also, isolation of reactor water can be achieved and leakage of reactor water to the exterior can be prevented by sealing cracks by clad welding using filler metal with respect to locations where stress corrosion cracking has already occurred.
When performing laser welding, metal evaporation or sputtering (sputter), termed fumes, are generated from the region that is being processed. A protective glass window is therefore provided, to ensure that such fumes or sputtering (sputter) do not enter the optical system within the laser irradiation head, or the laser processing is performed while spraying processing gas.
In laser welding, a known technique for guaranteeing quality of the region that is being welded is the technique of using a monitoring device to display the laser processing condition in the form of an image (see for example patent reference 1). With this technique, the laser processing condition is controlled by performing image recognition of the positional information of the weld pool or groove formed when the laser beam is directed onto the surface of the region to be processed: in this way, a welding region of stable quality can be formed. Such a technique is disclosed in Japanese issued patent number 3752112 (hereinafter referred to as patent reference 1).
In laser processing, deposition (or adhesion) of fumes or sputter generated during the laser processing on the protective glass screen or lens or the like of the laser irradiation head impairs the health of the laser irradiation head and may cause lowering of the laser power that irradiates the surface of the region to be processed. Although a conventional monitoring device as described above makes it possible to evaluate the quality of the welded region, it is still not possible to confirm the health of the laser irradiation head. Also, in confirming the health of the laser irradiation head, the only method available is to disassemble the laser irradiation head: thus time is required for the inspection and there is also the problem that, if a need for reprocessing is found, it is not possible to conclude to what point such reprocessing should return.
The present invention was made in order to deal with these circumstances, its object being to provide a laser irradiation device and a health diagnosis method of a laser irradiation head whereby it is possible to confirm health of a laser irradiation head without difficulty, without disassembling the laser irradiation head.
A laser irradiation device having
a laser oscillator that generates a laser beam;
a laser irradiation head that performs laser processing by directing a laser beam generated by said laser oscillator onto a region to be processed; and
a transmission mechanism that gets said laser beam through emitted from said laser oscillator to said laser irradiation head,
wherein said laser irradiation head comprises:
a protective glass window arranged in an emission region that emits said laser beam of said irradiation head onto said region to be processed;
a reflection mechanism, provided within said irradiation head, that gets said laser beam through and reflects at least visible light, of reflected lights from said region to be processed;
an image pickup camera that inputs light reflected by said reflection mechanism; and
an image adjustment optical system, provided between said reflection mechanism and said image pickup camera, whereby a focal point position of said image pickup camera can be changed over to the position of at least said protective glass window and said region to be processed.
A method of diagnosing the health of a laser irradiation head, there being provided:
a laser oscillator that generates a laser beam;
a laser irradiation head that performs laser processing by directing a laser beam generated from said laser oscillator onto a region to be processed; and
a transmission mechanism that gets said laser beam through generated from said laser oscillator to said laser irradiation head; and
said laser irradiation head comprises:
a laser beam adjustment unit that produces a laser beam directed onto said region to be processed by adjusting said laser beam from said transmission mechanism; and
a protective glass window arranged in an emission section that emits a laser beam; and
wherein a health of said laser irradiation head of said laser irradiation device is diagnosed;
there are arranged in said laser irradiation head:
a reflection mechanism provided within said irradiation head, that gets said laser beam through and that reflects at least visible light of reflected lights from said region to be processed;
an image pickup camera that inputs said light reflected by said reflection mechanism; and
an image adjustment optical system provided between said reflection mechanism and said image pickup camera, capable of changing over a focal point position of said image pickup camera to at least a position of said protective glass window and said region to be processed; and
said health of said laser irradiation head is diagnosed using an image picked up by said image pickup camera.
With the present invention, the health of the laser irradiation head can be confirmed without difficulty, without disassembling the laser irradiation head.